The invention relates to a data carrier which includes receiver means for receiving an amplitude modulated carrier signal which is amplitude modulated in dependence on data to be received and consists of high segments of high amplitude and pause segments of reduced amplitude, and also includes a circuit which is connected to the receiver means and includes the following means: data regeneration means whereto the received amplitude modulated carrier signal can be applied and whereby the data modulated on the carrier signal can be regenerated, and data processing means whereto the regenerated data can be applied and whereby the regenerated data can be processed.
The invention also relates to a circuit which includes the following means: data regenerating means whereto a received amplitude modulated carrier signal, amplitude modulated in dependence on data to be received and consisting of high segments of high amplitude and pause segments of reduced amplitude, can be applied and whereby the data modulated on the carrier signal can be regenerated, and data processing means whereto the regenerated data can be applied and whereby the regenerated data can be processed.
A data carrier of the kind set forth in the first paragraph and a circuit of the kind set forth in the second paragraph are known, for example from the patent document U.S. Pat. No. 5,345,231 A. The known data carrier is a so-called passive data carrier which does not include a separate power supply source but extracts the power required for a data processing operation from the amplitude modulated carrier signal applied to the data carrier, that is to say by means of supply voltage generating means which are formed essentially by a rectifier stage and a voltage control or voltage limiting stage. The data regenerating means in the known data carrier include a demodulator whereby the data modulated on the amplitude modulated carrier signal can be regenerated. The regenerated data can be applied to a control unit which is formed by a microcomputer. Therein, the control unit, i.e. the microcomputer, and storage means constitute data processing means whereto the regenerated data can be applied and whereby the regenerated data can be processed, for example in order to be stored in the storage means.
In the known data carrier, or in the known circuit of this data carrier, in the case of a data receiving operation the data regenerating means as well as the data processing means are activated in a normal operating mode for the entire duration of the data receiving operation, so that the data regenerating means as well as the data processing means require power which is thus consumed; consequently, the supply voltage generating means are loaded to a comparatively high degree during such a data receiving operation. This is problematic notably because during such a data receiving operation practically no power is applied to the data carrier in the pause segments of the amplitude modulated carrier signal but power is consumed nevertheless during these pause segments. Consequently, there is a disadvantageously high power consumption, leading to a reduced range of the data carrier or the circuit.
It is an object of the invention to avoid the described problems and to provide an improved data carrier and an improved circuit in which the power consumption during a data receiving operation is significantly reduced in comparison with the known data carrier or the known circuit.
In order to achieve the described object a data carrier of the kind set forth in the first paragraph according to the invention is characterized in that with the data regenerating means there are associated receiving storage means which are constructed and arranged to store regenerated data in conformity with a given data quantity, that the data regenerating means additionally include detection means which are capable of detecting the fact that regenerated data in conformity with the given data quantity has been regenerated by the data regenerating means and stored by the receiving storage means, and whereby, upon detection of this fact, control information can be generated and applied to the data processing means, that the data processing means are constructed so that they can be switched between a normal operating mode and a power saving operating mode, that the data processing means can be switched, in dependence on the control information, from their power saving operating mode to their normal operating mode and that when the data processing means are switched to their normal operating mode, the regenerated data stored in the receiving storage means can be transferred to the data processing means.
In order to achieve the described object, a circuit of the kind set forth in the second paragraph according to the invention is characterized in that with the data regenerating means there are associated receiving storage means which are constructed and arranged to store regenerated data in conformity with a given data quantity, that the data regenerating means additionally include detection means which are capable of detecting the fact that regenerated data in conformity with the given data quantity has been regenerated by the data regenerating means and stored by the receiving storage means, and whereby, upon detection of this fact, control information can be generated and applied to the data processing means, that the data processing means are constructed so that they can be switched between a normal operating mode and a power saving operating mode, that the data processing means can be switched, in dependence on the control information, from their power saving operating mode to their normal operating mode and that when the data processing means are switched to their normal operating mode, the regenerated data stored in the receiving storage means can be transferred to the data processing means.
Using only simple means, the steps according to the invention simply ensure that, during a data receiving operation involving a data carrier according to the invention or a circuit according to the invention, only the means which are absolutely required for receiving and regenerating data are activated, i.e. the data regenerating means, whereas the data processing means, having a significant power consumption in their normal operating mode, are practically deactivated during a significant part of a data receiving operation, i.e. switched to an energy saving operating mode, and are switched to their activated state, i.e. their normal operating mode, only during a comparatively short period of time in order to take up regenerated data from the data regenerating means. This results in a very significant saving of power during a data receiving operation by a data carrier according to the invention or a circuit according to the invention; this advantageously leads to a comparatively large range.
Attractive further embodiments of a data carrier according to the invention, or a circuit according to the invention, are characterized by the steps disclosed in the Claims 2 to 10 and 12 to 20.
The above and further aspects of the invention will become apparent from the embodiments described hereinafter and will be illustrated on the basis of these embodiments.